RNA plays an important role in cellular regulation - either by its presence in active form or an inactive form - or even by its total absence. In order to examine the role of processing enzymes in controlling gene function, an examination of the attack of eukaryotic messenger and ribosomal RNAs has been performed indicating that cleavage of these completed (i.e., previously processed) RNAs occurs under conditions of high enzyme to substrate ratios. Although this sort of degradation can be used to analyze the primary and secondary structure of such RNAs, great care must be used in order to determine whether precursor molecules are converted to their appropriate "processed" structures. A second regulatory protein, the termination factor rho, shows an interesting dependence of cytidylic acid residues in RNA for a nucleoside triphosphatase activity. Oligonucloetides of cytidylic acid longer than 12 residues are able to support the phosphatase activity but poly C or poly (A, U, C) give more activity at lower concentrations.